1. |
The influence of MgO, K2O, Na2O and gas pressure on slag foaming behaviour under reducing conditions |
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Archiv für das Eisenhüttenwesen,
Volume 65,
Issue 6,
2016,
Page 213-218
Jinguo Ren,
Michael Westholt,
Klaus Koch,
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摘要:
Using a photoelectric measuring technique to determine the foaming behaviour of iron oxide‐containing slag, investigations were carried out into the influences of magnesium oxide and the alkali oxides K2O and Na2O on melt foaming behaviour under reducing conditions. An MgO content of just a few percent intensifies the foaming action of acidic and self‐fluxing melts. This behaviour is also induced by a relatively low addition of alkali oxide. If the magnesium oxide and alkali oxide addition is further increased, slag volume growth during foaming declines. With basic compositions, both the magnesium oxide and the alkali oxides may reduce the volume increase of the foaming slag. Overall, melts undergo maximum foaming under conditions of medium basicity and in the medium temperature range. Alkali oxides promote the phenomenon of melt resolidification often observed in the tests. Tests with different furnace gas pressures up to max. 3 bar reveal that foaming volume of the melt increases with rising gas pressures.
ISSN:0003-8962
DOI:10.1002/srin.199401060
出版商:Wiley
年代:2016
数据来源: WILEY
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2. |
Nitrogen transfer into plasma heated steel melts as a function of arc polarity |
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Archiv für das Eisenhüttenwesen,
Volume 65,
Issue 6,
2016,
Page 219-224
Dieter Neuschütz,
Yuyou Zhai,
Alejandro Hauck,
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摘要:
Heating liquid steel in the tundish with argon stabilized plasma arcs is one example of the increasing importance of mobile and inert heating systems in metallurgy. Unwanted nitrogen pick‐up caused by infiltrated air, and possibly aggravated by the activating effect of plasma, should be minimized by selecting the optimum current mode and torch polarity. With this aim in mind, the nitrogen transfer kinetics have been investigated on 150‐kg low carbon steel melts at different nitrogen partial pressures as a function of arc polarity. The experimental plasma plant was equipped with a 2000‐A torch, housing a thoria stabilized tungsten electrode, and a counter electrode located at the bottom of the crucible. The torch could be operated with DC of either polarity or with AC. Kinetic models of nitrogen transfer have been developed, which show good agreement with experimental results. Arc polarity has a significant effect both on the rate of nitrogen pick‐up in the arc area (pumping effect) and on the mass transport in the melt (stirring effect). Of all configurations tested, the torch as cathode is the most suitable arc configuration for inert heating, since the particularly active N+ions in the plasma are repelled by the melt surface. Furthermore, the relatively strong stirring effect of the plasma jet leads to the highest heat transfer efficiency. On the other hand, where controlled nitrogen pick‐up is required, the highest nitrogen transfer rates are obtained with the torch poled as anode.
ISSN:0003-8962
DOI:10.1002/srin.199401061
出版商:Wiley
年代:2016
数据来源: WILEY
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3. |
Thermal modelling and stress analysis in the continuous casting of arbitrary sections |
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Archiv für das Eisenhüttenwesen,
Volume 65,
Issue 6,
2016,
Page 225-233
M. Reza Aboutalebi,
Mainul Hasan,
R. I. L. Guthrie,
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摘要:
A three‐dimensional parabolic heat conduction model has been developed to analyze heat transfer and solidification in variously shaped continuous casters. A fixed grid source based enthalpy method was used to model solidification during a casting process. In order to correctly model arbitrary cross‐sectional shaped castings, a body‐fitted coordinate transformation (BFT) technique was employed to transform the physical space on to a rectangular computational domain. The transformed governing equations and boundary conditions were solved in the transformed plane. Two arbitrarily shaped casters, having dog‐bone, and hexagonal cross‐sections, were tested in this study. The governing equations were discretized using the control‐volume finite difference approach, wherein an implicit solution technique was employed to solve the set of discretized algebraic equations.From the temperature field predicted by heat flow model, a quasi‐non‐linear stress analysis was carried out within the solidifying shell of the beam blank (dog bone) section. The effect of roller arrangement on the distortion of solidified shell was investigated.
ISSN:0003-8962
DOI:10.1002/srin.199401062
出版商:Wiley
年代:2016
数据来源: WILEY
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4. |
Tests on the oxidation‐inhibiting effect of CaB6in refractory MgO‐C materials |
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Archiv für das Eisenhüttenwesen,
Volume 65,
Issue 6,
2016,
Page 234-237
Tadeusz Rymon‐Lipinski,
Bettina Schmelzer,
Stanislaus Ulitzka,
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摘要:
The oxidation‐inhibiting action of B4C as an antioxidant is to be attributed to two possible mechanisms. The first describes the formation of reactive gases (Mg vapour and B2O2) that react with oxygen reducing its partial pressure in pores of the material. The second mechanism results in the formation of a borate layer which includes carbon between the oxide grains and thus protects it from further oxidation. The present study made an examination as to whether these mechanisms also play a part in the use of CaB6. The results confirm the pattern of chemical behaviour in MgO‐C materials with boron‐containing antioxidants recorded in previous tests. However, the temperature at which the protective effect begins lies in this case at about 200°C lower when compared to B4C. It is obviously due to the formation of a eutectic melt in system MgO‐CaO‐B2O3at approx. 1080°C.
ISSN:0003-8962
DOI:10.1002/srin.199401063
出版商:Wiley
年代:2016
数据来源: WILEY
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5. |
Simulation of the forming of mash seam welded sheets |
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Archiv für das Eisenhüttenwesen,
Volume 65,
Issue 6,
2016,
Page 238-241
Ulrich Draugelates,
Belkacem Bouaifi,
Dieter Sommer,
Dominic Seibert,
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摘要:
The paper presents results on the optimization of the process of mash seam welding for improving the formability of the joined sheet metal semi‐products. An integrated concept including the welding, smoothing and heat treatment of mash welded sheets has been developed. As an example, fatigue tests and the simulation of the forming behaviour of a mash seam welded tensile specimen simulated by the finite element method (FEM) is discussed. The determination of the material properties of the seam which, so far, have been determined experimentally is thus considerably simplified.
ISSN:0003-8962
DOI:10.1002/srin.199401064
出版商:Wiley
年代:2016
数据来源: WILEY
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6. |
The influence of thermomechanical treatment on the transformation behaviour of steels |
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Archiv für das Eisenhüttenwesen,
Volume 65,
Issue 6,
2016,
Page 242-247
Radko Kaspar,
Ulrich Lotter,
Christian Biegus,
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摘要:
The effect of thermomechanical treatment on the γ – α‐transformation in steel has been reviewed. It has been shown that the thermo‐mechanically conditioned austenite significantly influences the kinetics of transformation due to the differences in the formation of product phases. An enhanced nucleation during the diffusion controlled transformation, as a result of austenite grain refinement and/or austenite strengthening, leads to a substantial refinement of the microstructure (ferrite grains, pearlite nodules). The deformation substructure of austenite may strongly affect the shear mechanism of the diffusionless transformation, which leads to finely fragmented martensite crystals. Such differences in the transformation characteristics result in different formation temperatures of transformation products and so to the changes in CCT diagrams.
ISSN:0003-8962
DOI:10.1002/srin.199401065
出版商:Wiley
年代:2016
数据来源: WILEY
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7. |
Dynamic recovery in Nb‐Ti IF steels during hot and warm working |
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Archiv für das Eisenhüttenwesen,
Volume 65,
Issue 6,
2016,
Page 248-253
Yeong‐Tsuen Pan,
John G. Lenard,
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摘要:
Three ultra low carbon interstitial free steels, containing niobium and titanium, and a plain carbon steel were prepared to investigate their flow behaviour during hot and warm working. When the steels were subjected to compression at constant strain rates in the austenite region they exhibited typical work hardening and dynamic restoration behaviour. When they were worked in the ferrite region, they showed unusual and unexpected behaviour, featuring a rapid and quasi‐linear increase in flow stress at a low strain value, followed by a decrease with further increasing strain. Such abnormal flow behaviour was attributed to the presence of dissolved Nb atoms. When the niobium precipitated or when the steel was free from Nb, the typical work hardening and dynamic restoration curves were obtained during deformation in the ferrite region as well.
ISSN:0003-8962
DOI:10.1002/srin.199401066
出版商:Wiley
年代:2016
数据来源: WILEY
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8. |
Assessment of intrinsic creep resistance evolution based on the results of constant load creep tests |
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Archiv für das Eisenhüttenwesen,
Volume 65,
Issue 6,
2016,
Page 254-259
Spiros G. Pantelakis,
Nikolaos I. Vassilas,
Essam A. El‐Magd,
Karl F. Rix,
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摘要:
In the present study a method to assess the intrinsic creep resistance evolution by using data of constant load creep tests is proposed. The investigation has been performed on the austenitic steels X6 CrNi 18 11 and X8 CrNiMoNb 16 16. To develop the constitutive equation describing the intrinsic creep resistance evolution a simple structural mechanical model has been used. The applied model is based on a modification of the Levy‐Mises equation for plasticity to consider creep time effects. The proposed model has been verified experimentally. The experimental creep resistance evolution curves have been derived with the aid of strain transient dip test performed in transient, steady state and accelerated creep stage.
ISSN:0003-8962
DOI:10.1002/srin.199401067
出版商:Wiley
年代:2016
数据来源: WILEY
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